1. Field of the Invention
The present invention relates to a pedestrian airbag system including a hood panel and an airbag to be accommodated in a position near the rear end thereof in a folded manner.
2. Description of the Related Art
In the related art, there exists a pedestrian airbag system which is disclosed in JP-A-2003-89333. In this airbag system, a case for accommodating an airbag to be disposed near the rear end of a hood panel is formed of synthetic resin and provided separately from the hood panel, and when the airbag is deployed and inflated, the airbag is adapted to be projected from an opening formed by breaking a part of the case.
However, in the pedestrian airbag system as set forth in the above-described patent publication, when the airbag is projected upward at the initial stage of airbag inflation, the case cannot resist a reaction force exerted to the case, and hence there exists a problem in stabilizing the direction of projection of the airbag. This is because the entire case for accommodating the airbag is formed of synthetic resin.
There also exists a pedestrian airbag system disclosed in JP-A-2003-306101. In this airbag system as well, a case disposed near the rear end of a hood panel for accommodating an airbag is formed of synthetic resin. In the airbag system as disclosed in the above-described patent publication, the upper side of the case is fixed to the rear end side of the hood panel, and when the airbag is deployed and inflated, the airbag can be projected from an opening formed by breaking a part thereof. Therefore, in the same manner, when the airbag is projected upward at the initial stage of airbag inflation, the case cannot resist the reaction force exerted to the case, and hence there exists a problem in stabilizing the direction of projection of the airbag. This is because the case is fixed to the rear side of the hood panel at the upper side.
In addition, in the pedestrian airbag system disclosed in the latter patent publication described above, since the portion covering the opening which is opened when the airbag is deployed and inflated is formed of synthetic resin, a break appears between this and the sheet metal outer panel of the hood panel disposed therearound due to difference in material, whereby design of the portion near the mounting portion of the airbag system is deteriorated.
There also exists a pedestrian airbag system disclosed in JP-A-7-125607, in which a case accommodating an airbag and an inflator is disposed substantially at the center of the hood panel in the longitudinal direction. Normally, since the pedestrian airbag system is provided with a heavy inflator, the overall weight increases. Therefore, as in the related art, when the case accommodating the airbag and the inflator is mounted substantially at the center of the hood panel in the longitudinal direction, there arises a necessity to increase rigidity of the portion of the hood panel which supports the case, to allow the hood panel to receive the reaction force which is exerted downward when the airbag is projected upward in the initial stage of airbag inflation and still support the pedestrian airbag system with reliability. In particular, since the inflator is required to be fixed firmly, the hood panel must be given increased weight in order to increase rigidity of the portion for supporting the inflator.
In addition, as in the related art, in the case of the pedestrian airbag system having a structure in which the case which accommodates the airbag and the inflator is mounted substantially at the center of the hood panel in the longitudinal direction, the case vibrates significantly with the hood panel when the vehicle is traveling, and hence may collide with parts in an engine room disposed downwardly of the case. Therefore, in order to reduce vibrations of the case, it is necessary to increase rigidity of the portion of the hood panel for supporting the case.
There is also a pedestrian airbag system as disclosed in JP-A-2004-90795. In this airbag system, an opening for allowing an airbag to project is formed on an outer panel of a hood panel, and the opening is covered by a flap portion formed of the same sheet metal as the outer panel.
However, in the airbag system configured as described above, a break appears between the flap portion and the outer panel surrounding therearound, and hence design of the portion near the mounting portion of the airbag system is deteriorated.